This invention relates to selection and display systems and, more particularly, to an arrangement for minimizing the number of leads between such a system and a system controller.
The present invention is particularly concerned with a system capable of performing a plurality of functions, each of which is operator selectable by the actuation of a switch dedicated to that function, the system providing visual feedback to the operator of that function selection by controlling the energization of an indicator associated therewith. Prior art controller circuitry typically required an input lead from the switch and a separate output lead to the indicator. With the advent of integrated circuits for use as system controllers, the number of connections between an integrated circuit chip and the outside world becomes a serious design criterion because of the limited number of input/output terminals available on the integrated circuit chip. It is therefore a desirable objective to minimize the number of connections between a selection and display arrangement and an integrated circuit controller. In the past, there have been many proposals for limiting the number of connections. These proposals typically involve a first matrix array of the switches and a second matrix array of the indicators. However, such an arrangement is not efficient when a relatively small number of switches and indicators are used. For example, in a system having nine switches and nine corresponding indicators, the switches being in a 3.times.3 matrix array and the indicators also being in a 3.times.3 matrix array, a total of 12 leads are required.
It is therefore an object of this invention to minimize the number of connection leads between a selection and display arrangement and a system controller.
It is another object of this invention to provide a connection arrangement for a selection and display system which utilizes only a single lead for each associated pair of switches and indicators.